Trichloroacetic Acid as Additional Factor Contributing to Desertification in Southern Africa

There has been an accelerated expansion of deserts in the past five decades. Recent data reveal that the atmogenically formed organic compound, trichloroacetic acid (TCA) is a contributory factor in addition to anthropogenic and natural sources. The aim of this study was to use TCA as an indicator for the possible occurrence of C₂-chloroacetic acids; to assess the burden on the vegetation by using pine needles as a bio-indicator system and to deliberate on the possible role of TCA in the dynamics of the vegetation in southern Africa. Field experiments conducted on pine trees and on C₃ and C₄ crop plants under controlled laboratory conditions, have revealed that plants could be influenced positively or negatively by TCA. To obtain an integrated assessment of the pollution emission over a time span of at least one year, two-year-old pine needles of different Pinus species were used as a bio-indicator for TCA pollution at different measuring sites. The data of our investigation clearly indicate that areas exist in South Africa where the vegetation is burdened by ecotoxicologically relevant TCA contents comparable to those in central Europe and southern Russia where TCA was shown to play a role in the destabilisation of the steppe vegetation.     

Water Development Strategy as a Driving Force for Sustained Rangeland Management by Local Communities in Sub-Saharan Africa

Water is the major food component for the maintenance of animals. Although Africa is endowed with diverse agricultural environments, the survival of animals in Sahelian and sub-Sahelian Africa is threatened by the lack of water. Animals need water as an essential nutrient, a component of the body, and for conductive or evaporative cooling. Water needs are met mainly through drinking free water and to a lesser extent by utilising water that forms part of the feed. However during the long dry season, surface water resources dwindle and the water content of available forage decreases, thereby increasing the animals’ demand for water. Consequently animals have to walk for long distances to obtain adequate forage and water, which in turn raises the demand for these resources. Water can be used to direct and regulate rangeland management in this open access environment, to maintain range resources and to improve their quality. Water development, which takes into consideration usable forage, despite some intra- or inter-annual variability, plays an important role and its spatial distribution will affect the grazing intensity of forage resources. Sound water development and management strategies integrating local communities in the decision-making will set up a firm basis for sustained range management in the free and open access environment of sub-Saharan Africa where lack of financial input, social and cultural habits and above all the environmental condition do not permit large scale fencing as in other parts of the world.     

The Role of Soil Surface Crusting in Desertification and Strategies to Reduce Crusting

Soil crusting decreases infiltration, increases erosion, and impedes vegetation establishment, so reducing the impact of crusting is of major importance in combating desertification. Although surface crusting has been the subject of considerable research over the past 50 years or more, the practical management of soil crusts remains a challenge for many dryland communities. Crusting occurs in two steps, an initial aggregate breakdown period that occurs under rainfall and a subsequent hardening phase during drying. Several factors influence crust development, but the single most important one is soil aggregate stability. Strategies to reduce crusting can be based either on protecting the surface from raindrop impact or improving aggregate stability, or a combination of both. However, crust control is labor and/or capital intensive and must be thought out clearly in terms of the benefits to be achieved.     

Land User Participation in Developing a Computerised Decision Support System for Combating Desertification

Combating desertification in natural rangelands has recently become a priority in large parts of southern Africa. Rangeland managers, farmers, scientists, conservationists and land users have been applying a variety of restoration technologies to address this problem. Bush encroachment, as part of the desertification process, involves the natural replacement of the herbaceous plant cover by undesirable problem woody species. The active and passive restoration technologies that are applied, are mainly based on indigenous knowledge and include the chemical, mechanical or manual reclamation of unproductive rangelands, as well as the combating of woody and alien species encroachment. Indigenous practices and knowledge play a major role in the effectiveness and success rate of these technologies. This project faces the challenge of bringing together both local and scientific knowledge in a single user-friendly, computerised Decision Support System (DSS) which is directly accessible by land users to support them in the process of decision making, concerning the combating of desertification. Case studies from central and northern Namibia were used to combine qualitative and quantitative data to develop this Decision Support System. The DSS currently consists of two databases and an expert system, which evaluates the results of land users’ management practices, and provides easily accessible information and advice for participants in the system, based on the incorporated data. The DSS is also linked to national and international web sites and databases to offer a wider range of information on technologies concerning agricultural and conservation practices.     

对旱情的理性思考和构建新的监测、抗旱理念

对旱灾造成的损失,不能仅从农业粮食减产单方面估算,而应把旱灾造成的隐性损失科学评估出来。据此提出,抗旱要处理好农业用水、工业用水和城市用水及生态用水的关系,真正实现水资源的可持续利用,并应建立自动化的干旱监测和快速评估系统,以保证及时掌握旱情,将旱灾损失减至最小。     

甘家湖湿地边缘带土地荒漠化演变中土壤颗粒分形特征

采用分形理论,研究了甘家湖湿地边缘带不同景观变化类型土壤颗粒体积分形维数的特征。结果表明,（1）从芦苇湿地边缘、胡杨林土、梭梭灌木林土、芦苇湿地、耕地周边、耕地到盐化草甸土的土壤粒径变化可以看出：湿地边缘带土壤荒漠化演变中砂粒含量在逐渐上升,粉粒、粘粒含量逐渐下降。这表明湿地边缘带人为的放牧、开垦、牛羊践踏对土壤产生了...     

Community Based Interventions as a Strategy to Combat Desertification in the Arid and Semi-Arid Rangelands of Kajiado District, Kenya

Vegetation degradation, especially the disappearance of woody vegetation and a diminished grass cover, has aroused the concern of the Maasai community (semi-nomadic pastoralists) of Kajiado District, Kenya. The district is one of Kenya’s arid and semi-arid districts. Over recent years, they have observed their land resources deteriorate due to the desertification process caused by the land use practices of man. They have identified indicators of desertification such as increase of bare lands, which have been invaded by previously unknown grasses and weeds that are of no economic value, and also the disappearance of some useful plant species. It is due to the above concerns that a group of 30 farmers have been very keen to participate in on-farm research to strategize on ways to halt and even reverse the desertification process. The participatory research has identified useful trees that the farmers have been planting around homesteads, as woodlots on their farms to provide woodfuel, shade, and to act as windbreaks. They have also identified species for planting as live fences instead of using thorny tree branches as fencing material, which contributes further to the desertification process. Due to the termite menace on young tree seedlings, the farmers use indigenous knowledge to prepare concoctions using locally available materials, which they apply to planting holes and on seedlings. During awareness campaigns, the farmer research group highlights the need to conserve vegetation resources and also expounds on the concept of planting two trees after one is felled.     

粤北地区干旱监测及预警方法研究

从农业生产实际出发,引入能够判断作物受旱程度的毛管破裂含水量、凋萎含水量等土壤含水量指标来确定干旱指标,根据土壤水分平衡理论,建立干旱监测预警模型,利用自动站气象资料和降水趋势预报对干旱情况进行判别和分析,并采用Surfer软件对干旱情况进行直观的图形显示.     

Community Production Practices and Desertification in the Sahelo-Sudanian Region of Cameroon at the Turn of the Millennium

The Sahelo-Sudanian region of Cameroon extends over 10 million hectares. Varied flora and soil types, a complex mosaic of vegetation and plant communities and a diversified wild animal population are the major natural resources of this region. Desertification in the region can be related to two major known causes: a. short or long-term drought due to short-term or long-term climatic trends toward aridity; b. human activities which degrade the biological environment. Globally, humans generally have less effect on desertification than climatic change in the short run. The only strategy to fight against this situation particularly in the developing countries is to withdraw populations from the areas and to settle them elsewhere. However, most local or regional desertification processes in general, and in the Sahelo-Sudanian region in particular, are due to the misuse or unsound exploitation of natural resources by humans and their animals. Often, comprehension of the complexity of even small interactions between parameters affecting our local environment remains limited. Poor economic assessments of the long-term benefits of proper natural resource conservation and management increase the extent of the exploitation, in turn increasing the degradation process. Yet ecologically sound management of natural resources integrating indigenous knowledge and basic population interest and concern can secure restoration in several areas and sustained productivity of Sahelo-Sudanian lands.     

Combating Desertification: Building on Traditional Knowledge Systems of the Thar Desert Communities

The Thar Desert of western India is known for its rich and ancient culture system and traditions. The communities have long been part of the Thar Desert ecosystem and have evolved specific strategies to live in harmony with its hostile environment. This culture has provided several miracle plants of immense food and medicinal value to modern civilisation. The ancient rural livelihood knowledge system reflects time-tested techno-scientific knowledge with a proven track record of sustainability, especially during natural hazards like drought and famines. In addition, several of the traditional skills of local communities in arts and crafts, music and instruments have made modern man aware of the art and techniques of sustainably utilising local biological resources and preserving their biodiversity along with using waste products of the forests, without harming the desert ecosystem. Traditional cultural and socio-religious values are fast dwindling under the impact of materialistic approach, industrialisation and development. This paper endeavours to illustrate the need to assist and propagate indigenous rural livelihood systems rather than mindlessly replace or abandon them as a result of state bureaucracies.     

Assessment of Benthic Infaunal Condition on the Mainland Shelf of Southern California

Benthic infauna were sampled from 251 Southern California Bight (SCB) mainland shelf sites in the summer of 1994. Sample sites were selected using a stratified random design, with the primary strata being depth zone, geography, and proximity to point and non-point discharges. Benthic infaunal condition was assessed using the Benthic Response Index (BRI), and by comparing dominant taxa and community parameters (e.g., number of taxa) among strata. Ninety-one percent of sediments in the SCB were found to contain healthy benthic communities. Most stations with altered benthos were located near river mouths, in Santa Monica Bay, or on the Palos Verdes Shelf. Deviations at sites with altered benthic communities were mostly limited to minor changes in species composition, rather than to large declines in diversity or abundance.     

基于RS和GIS的干旱荒漠区域土壤侵蚀动态监测与评价

为建立土壤侵蚀动态变化数据库,本文以土地利用数据、植被覆盖指数、最大风速等值线图和DEM数据为信息源,对干旱荒漠区新疆克拉玛依市2000年和2007年的土壤侵蚀状况进行了动态监测与评价。结果表明,受自然条件和人类活动影响,8年间克拉玛依市土壤侵蚀强度有所增加,变化区域主要集中在克拉玛依市中部平原区。该方法的应用实现了土壤侵蚀的定时定量评价。     

1976-2005年唐山地区降水变化规律及干旱预测

利用唐山市1976-2005年各县年降水序列,分析了该市降水的空间分布规律和时间变化特点。采用灰色系统的灾变预测方法,对各县分别建立了GM（1,1）模型,进行未来25年唐山市各站的干旱年预测。利用残差检验、后验差检验和关联度检验对各模型分别进行了精度检验。结果表明,预测模型精度较高,可以对唐山市各县未来的干旱年进行预测,从而为科学决策提供依据。     

Connecting Community Action and Science to Combat Desertification: Evaluation of a Process

Combating desertification requires the involvement of many people ranging from communities who experience the effects on a daily basis and scientists attempting to understand the biophysical and socio-economic causes and consequences of desertification, to developers and policy makers on all levels. In many instances, however, the understanding, approaches and actions of these different groups contradict rather than support one another. Over the period 2000 to 2002, a conference process undertaken in southern Africa brought together communities, scientists, and development workers to test the concept that they could connect and work together to combat desertification, given an appropriate framework. The conference was a success, and communities, scientists and developers did exchange experience, knowledge and information. Many lessons were learned, although some pitfalls were experienced. Time, funding, enhanced communication, and good will are the primary ingredients for ensuring that different sectors complement one another in their efforts to combat desertification.     

Desertification of the eastern Karoo,South Africa: Conflicting paleoecological,historical, and soil isotopic evidence

The desertification debate in South Africa has benefitted greatly in recent years from the contributions of a wide range of disciplines. In this paper we review the conflicting and supporting evidence for degradation in the eastern Karoo as reported in recent archaeological, historical, and stable carbon isotope studies as it relates to three key aspects of the debate: the precolonial environment, the rate and nature of change, and the relative contributions of humans and climate to the process. First, all studies suggest a greater grassiness at some time in the past, but researchers disagree on the timing of the switch to more shrubby conditions in the eastern Karoo. Second, regional rainfall records for the past 2 decades reveal an above-average rainfall period, and numerous long-term surveys show an increase in grass cover over the same period. These findings question the expanding Karoo hypothesis as well as the argument that the Karoo's carrying capacity has decreased in recent years. Finally, the relative responsibilities of humans and climate in the degradation process remain poorly understood and generally have not formed the focus of investigation.     

Assessing the performance of SIA in the EIA context: A case study of South Africa

This article, a theoretical perspective based on a literature study, is a critical evaluation of SIA as part of the EIA process in South Africa against the background of international guidelines and best practices. It includes sections on the historical background of the development of SIA in South Africa, the legal status and requirements of SIA in the country, and a critical evaluation of SIA regulation in South Africa. The conclusion reached in the article is that the persistent problems of SIA practice, experienced in other parts of the world, are also evident in South Africa. Apart from institutional, financial and professional constraints, there are also serious problems associated with approach and methods. This conclusion confirms the findings of empirical studies that SIA in South Africa is neglected, that the practice of SIA in South Africa is not yet on a sound footing, and that it does not receive the professional attention it deserves in a country beset by enormous social challenges. To conclude the article recommendations are made to improve the level of SIA practice in South Africa, and the possible significance of this national case study for international practice is indicated.     

Environmental Management in the Industrial Enterprises of the South of Spain

The eighties were notable for awareness of the need to prevent defects and for orientation towards the client to improve the competitiveness of industrial enterprises. This objective of zero defects has meant for many enterprises a management orientation to zero environmental impact. In this article we analyse the special situation of industrial enterprises in Andalusia (Spain) in the establishment of environmental management systems, proposing a matrix of strategies for their development based on the analysis of strengths, weaknesses, opportunities and threats.     

Air Quality Monitoring and Management in Lisbon

The environmental decision-making process is related with the interpretation of data both in spatial and temporal dimensions. This paper presents a methodology that integrates the time-space framework of air quality data to infer the temporal pattern and spatial variability that could be interpreted for environmental decision purposes. Variograms that accommodate time and space lags were used for the analysis and proved to be effective. Its environmental meaning, in particular its relationship with traffic patterns is discussed. Data from air quality monitoring stations located in the central part of Lisbon were used in this study. It describes a strategy to identify the type of vehicles responsible for certain pollutant levels, particularly for nitrogen oxides, and discusses the application of new air quality European legislation to the city of Lisbon, Portugal.     

学习先进理念、促进环境监测管理水平提升

通过在意大利的考察学习,对学习考察的收获和感受进行了总结,并结合意大利现行环境政策和环境监测先进经验提出了我国在环境保护和监测管理方面的设想和建议,供同行参考。     

Multi-Criteria and Multi-Perspective Analysis of Contaminated Land Management Methods

Errors in environmental resource management over the years have created pollution problems in some areas which are difficult to handle, regardless of the development of knowledge and technologies. This is particularly true in the case of soil pollution. The negative effects of persistent pollutants have been observed for a long time. For instance, lead and cadmium remain in the soil for centuries, during which time they are absorbed by plants and simultaneously cause secondary air pollution. The authors made an attempt to describe and assess the possible options of dealing with the problem of contaminated land in Katowice District. Considering the necessity of a multilateral approach, a pairwise comparison technique has been chosen as the most suitable to show the complexity of the problem. The different variants of actions aimed at preventing the pollutants from getting into the food chain were analyzed against a set of criteria, consisting of the following issues: time, cost, effectiveness, social acceptance, feasibility. The relative importance of actions were judged by the team of experts using the Saaty method. Also, a two-perspective assessment (the two different stakeholders), which involves considering the perspective of an owner of a piece of contaminated land and an ecologist has been performed. The results of comparative, multicriteria and multi-perspective assessment indicate the following:- the best method for contaminated agricultural land management is willful and controlled cultivation,- other recommended actions are deep ploughing and phytoremediation,- there is not much acceptance for the other methods.